Cu-Ti thin films were fabricated using a combinatorial sputtering system to realize highly sensitive surface acoustic wave (SAW) devices. The Cu-Ti sample library was grown with various chemical compositions and electrical resistivity, providing important information for selecting the most suitable materials for SAW devices. Considering that acoustic waves generated from piezoelectric materials are significantly affected by the resistivity and density of interdigital transducer (IDT) electrodes, three types of Cu-Ti thin films with different Cu contents were fabricated. The thickness of the Cu-Ti thin films used in the SAW-IDT electrode was fixed at 150 nm. As the Cu content of the Cu-Ti films was increased from 31.2 to 71.3 at%, the resistivity decreased from 10.5 to 5.8 × 10-5 ohm-cm, and the density increased from 5.5 to 7.3 g/cm3, respectively. A SAW device composed of Cu-Ti IDT electrodes resonated at exactly 143 MHz without frequency shifts, but the full width at half maximum (FWHM) values of the resonant frequency gradually increased as the Cu content increased. This means that although the increase in Cu content in the Cu-Ti thin film helps to improve the electrical properties of the IDT electrode, the increased density of the IDT electrode deteriorates the acoustic performance of SAW devices.

Tb3+-doped CaNb2O6 (CaNb2O6:Tb3+) thin films were deposited on quartz substrates at a growth temperature of 300 °C using radio-frequency magnetron sputtering. The deposited thin films were annealed at several annealing temperatures for 20 min and characterized for their structural, morphological, and luminescent properties. The experimental results showed that the annealing temperature had a significant effect on the properties of the CaNb2O6:Tb3+ thin films. The crystalline structure of the as-grown CaNb2O6:Tb3+ thin films transformed from amorphous to crystalline after annealing at temperatures greater than or equal to 700 °C. The emission spectra of the thin films under excitation at 251 nm exhibited a dominant emission band at 546 nm arising from the 5D4 → 7F5 magnetic dipole transition of Tb3+ and three weak emission bands at 489, 586, and 620 nm, respectively. The intensity of the 5D4 → 7F5 (546 nm) magnetic dipole transition was greater than that of the 5D4 → 7F6 (489 nm) electrical dipole transition, indicating that the Tb3+ ions in the host crystal were located at sites with inversion symmetry. The average transmittance at wavelengths of 370~1,100 nm decreased from 86.8 % at 700 °C to 80.5 % at an annealing temperature of 1,000 °C, and a red shift was observed in the bandgap energy with increasing annealing temperature. These results suggest that the annealing temperature plays a crucial role in developing green light-emitting CaNb2O6:Tb3+ thin films for application in electroluminescent displays.

소고기의 건식 숙성 기간을 단축하고자 연육과 관련된 효소 활성이 높은 15-36oC 온도범위에서 저습도로 숙성할 수 있는 라디오파 숙성장치를 개발하였다. 이 장치는 평행 판 전극 사이에 소고기를 넣고 라디오파를 가하여 유전가열이 되는 현상으로 고기의 온도를 높였고, 냉풍을 이용하여 습도를 낮춰서 고기표면이 건조되게 하였다. 이 장치를 이용하여 2등급 소고기 채끝 부위를 숙성시킨 결과 40 W/ kg로 가열하여 고기 품온이 30oC를 초과하는 온도 범위 24 h 숙성할 경우 12.3%, 10-30oC 온도 범위에서 숙성시킬 경우 55.2% 연육효과가 나타났다. 라디오파 숙성 중 제상 과정 없이 냉풍을 계속 가할 경우 미생물 증식에 의한 문제가 발생하지 않았으며, 이러한 연육 효과는 기존 건식숙 성 21일간 절단강도 17% 감소하는 것에 비해 매우 단시간 나타난 것으로 숙성기간을 크게 단축할 수 있음을 확인 하였다. 닭고기와 돼지고기는 육질의 차이로 라디오파 숙성에 의한 연육 효과가 나타나지 않았다.

Prognosis of unresectable pancreatic cancer is poor with the rate of surviving more than 5 years is less than 10% despite multi-modalities treatment. The American Society of Clinical Oncology suggested that all patients with metastatic pancreatic cancer should be offered information about clinical trials. Endoscopic ultrasound guided radio frequency ablation has been recently used in patients with advanced stage pancreatic cancer in a few studies. This article has reviewed information from published articles using endoscopic ultrasound guided radio frequency ablation for advanced pancreatic cancer.

Powder quality, including high flowability and spherical shape, determines the properties of additively manufactured products. Therefore, the cheap production of high-quality powders is critical in additive manufacturing. Radio frequency plasma treatment is an effective method to fabricate spherical powders by melting the surface of irregularly shaped powders; in the present work, mechanically milled Zr powders are spheroidized by radio frequency plasma treatment and their properties are compared with those of commercial Zircaloy-2 alloy powder. Spherical Zr particles are successfully fabricated by plasma treatment, although their flowability and impurity contents are poorer than those of the commercial Zircaloy-2 alloy powder. This result shows that radio-frequency plasma treatment with mechanically milled powders requires further research and development for manufacturing low-cost powders for additive manufacturing.

The enamel powders used traditionally in Korea are produced by a ball-milling process. Because of their irregular shapes, enamel powders exhibit poor flowability. Therefore, polygonal enamel powders are only used for handmade cloisonné crafts. In order to industrialize or automate the process of cloisonné crafts, it is essential to control the size and shape of the powder. In this study, the flowability of the enamel powders was improved using the spheroidization process, which employs the RF plasma treatment. In addition, a simple grid structure and logo were successfully produced using the additive manufacturing process (powder bed fusion), which utilizes spherical enamel powders. The additive manufacturing technology of spherical enamel powders is expected to be widely used in the field of cloisonné crafting in the future.

In the present work, spheroidization of angular vanadium powders using a radio frequency (RF) thermal plasma process is investigated. Initially, angular vanadium powders are spheroidized successfully at an average particle size of 100 μm using the RF-plasma process. It is difficult to avoid oxide layer formation on the surface of vanadium powder during the RF-plasma process. Titanium/vanadium/stainless steel functionally graded materials are manufactured with vanadium as the interlayer. Vanadium intermediate layers are deposited using both angular and spheroidized vanadium powders. Then, 17-4PH stainless steel is successfully deposited on the vanadium interlayer made from the angular powder. However, on the surface of the vanadium interlayer made from the spheroidized powder, delamination of 17-4PH occurs during deposition. The main cause of this phenomenon is presumed to be the high thickness of the vanadium interlayer and the relatively high level of surface oxidation of the interlayer.

We investigate the radio properties of the dwarf galaxy SDSS J133245.62+263449.3 which shows optical signatures of black hole activity. Dwarf galaxies are known to host intermediate mass black holes (IMBHs) with masses MBH ∼ 10 4-6 M⊙, some of them being radio loud. Recently, Reines et al. (2013) found dwarf galaxy candidates which show signatures of being black hole hosts based on optical spectral lines. SDSS J133245.62+263449.3 is one of them; it shows a flux density of ∼ 20 mJy at 1.4 GHz, which corresponds to L 1.4GHz ∼ 10 23 WHz -1. This is much brighter than other black hole host dwarf galaxies. However, star formation activity can contribute to radio continuum emission as well. To understand the nature of the radio emission from SDSS J133245.62 + 263449.3, we imaged this radio loud dwarf galaxy at low frequencies (325 MHz and 610 MHz) using the Giant Metrewave Radio Telescope (GMRT). We present here the high resolution images from our GMRT observations. While we detect no obvious extended emission from radio jets from the central AGN, we do find the emission to be moderately extended and unlikely to be dominated by disk star formation. VLBI observations using the Korean VLBI Network (KVN) are now being planned to understand the emission morphology and radiation mechanism.

The Azuki bean weevil, Callosobruchus chinensis L., is a common insect pest of stored products in the world. Radio-frequencydependent oviposition, development and adult performances of C. chinensis were examined at five radio-frequencies of0 (control), 5, 10, 20, and 30 kHz on azuki bean, cowpea, and mung bean seeds. The effects were studied on two successivegenerations of C. chinensis. The results showed that radio-frequency application have significant effects on the life variablesof C. chinensis. Radio-frequency exposures on three seed species not only impacted on developmental time, adult longevityand adult weight but negative effects were also transmitted to the successive generations. Longer developmental time andthe least adults of C. chinensis were emerged with shorter longevity in case of radio-frequency treatment than untreated.Decreasing the radio-frequency level further reduced the adult longevity and increased time for development of adults.The least adult emergence and short longevity was recorded for 5 kHz treatment. Radio-frequency treatments have alsoaffected on the adult performance such as weight of adult. The life variables of C. chinensis are discussed in terms oftargeting susceptibilities to radio-frequencies in storage as an alternative to chemical treatments.

This study investigated the effects of 27.12 MHz radio frequency (RF) heating on heat transfer phenomena during the thawing process of frozen food. To determine the velocity of the RF thawing machine, samples were frozen at -80oC and subjected to different power treatments. The phase change times (-5 to 0oC) of frozen radish were 30, 26, 13, and 8 min; those of pork sirloin were 38, 25, 11, and 5 min; those of rump were 23, 17, 11, and 6 min; those of chicken breast were 42, 29, 13, and 9 min; and those of tuna were 25, 23, 10, and 5 min at 50, 100, 200, and 400 W, respectively. The heating limit temperatures of the radish, pork sirloin, rump, chicken breast, and tuna samples were 19.5, 9.2, 21.8, 8.8, and 16.8oC at 50 W; 23.5, 15.5, 27.3, 12.3, and 19oC at 100 W; 42, 26.9, 45.7, 22.1, and 39.4oC at 200 W; and 48.5, 54.7, 63.6, 57.3, and 44.9oC at 400 W. These results suggest that high-power RF improves thawing velocity and heating limit temperatures, and that an improvement on the operation of the RF thawing machine, according to food temperatures, is needed.

Low water activity foods usually do not support growth of pathogens. However, in recent years, a number of outbreaks associated with low water activity foods occurred, making people have a new understanding of microorganisms about low water activity foods and resulting in the safety of these foods becoming a major concern. Traditional thermal sterilization methods are difficult to be applied in low water activity foods because of its poor heat transfer and strong heat resistance of microorganisms. Radio frequency (RF) is considered as one of the most potential technologies in food industry and has an excellent prospect on content of the advantages of rapid and uniform heating. The Principle of RF-Sterilization is similar to Microwave, but RF has lower frequency and wider wavelength, therefore RF penetration depth is more suitable for Sterilization. For the pre-packaged food, there is few report on the effect of RF on the food and packaging materials. This presentation aims to discuss the influence of RF through comparing to Microwave.

The objective of this study was to assess RF-EMF exposure levels in indoor daycare centers in a Metropolitan city. RF-EMF measurements were collected and surveyed from 50 volunteer daycare centers in the Korea between October 2013 and October 2014. Through our research, it was found that the main exposure source for indoor daycare centers is the frequency bands for TV and Radio broadcasting (FM: 88.1~107.9 MHz), mobile phone (869~894 MHz, 1840~1870 MHz, 1885~2170 MHz), wireless LAN and home electronics, etc., including TRS, Wireless Data Communication. The RF-EMF exposure levels for all daycare centers were far below the recommended standards of EMF Guideline Korea and international reference levels proposed by ICNIRP (International Commission on Non-Ionizing Radiation Protection). However, in terms of long term health effects some uncertainty exists, and thus minimizing exposure may reduce this uncertainty. The data we collected will be useful data for determining RF-EMF management and risk communication at daycare centers.

We present results of our investigation of the radio intrinsic brightness temperatures of compact radio jets. The intrinsic brightness temperatures of about 100 compact radio jets at 2, 5, 8, 15, and 86 GHz are estimated based on large VLBI surveys conducted in 2001-2003 (or in 1996 for the 5 GHz sample). The multi-frequency intrinsic brightness temperatures of the sample of jets are determined by a statistical method relating the observed brightness temperatures with the maximal apparent jet speeds, assuming one representative intrinsic brightness temperature for a sample of jets at each observing frequency. By investigating the observed brightness temperatures at 15 GHz in multiple epochs, we find that the determination of the intrinsic brightness temperature for our sample is affected by the flux density variability of individual jets at time scales of a few years. This implies that it is important to use contemporaneous VLBI observations for the multi-frequency analysis of intrinsic brightness temperatures. Since our analysis is based on the VLBI observations conducted in 2001-2003, the results are not strongly affected by the flux density variability. We find that the intrinsic brightness temperature T0 increases as T0 ∝ νξ obs with ξ = 0.7 below a critical frequency νc ≈ 9 GHz where the energy loss begins to dominate the emission. Above νc, T0 decreases with ξ = −1.2, supporting the decelerating jet model or particle cascade model. We also find that the peak value of T0 ≈ 3.4 × 1010 K is close to the equipartition temperature, implying that the VLBI cores observable at 2-86 GHz may be representing jet regions where the magnetic field energy dominates the total energy in jets.

PTEF membranes are used for roofing materials of membrane structures. PTEF is the abbreviation of Poly-tetra Fluotide-ethylene. These materials are consisted of fiberglass weave and polyetrfluoroethylene coating. Also, PTEF membranes have some problems of structural capacity by wind or snow load, etc. In this study, sensor housings using lead switches are bonding in PTFE membranes, Monitoring to changes tension and tear damages are studied using radio frequency. If tension is received on edged membranes, bonded lead switches of sensor housings will be destroyed by changes tension, and these become to send signals of damages at the connected radio frequency system with increased tension. Study of these functional membrane materials will be contributed to prevent water leakage and long-term maintenance of membrane structures.

본 연구에서 리드스위치를 이용한 정적변위센서를 무근과 철근 콘크리트 보에 부착하고 균열손상의 모니터링을 위해 무선주파수를 이용하였다. 무근 콘크리트 보와 철근 콘크리트 보에 외력이 작용하면 균열손상이 발생하고 균열의 증진으로 정적변위센서가 파괴되면 이와 연결되어 있는 무선주파수 발신자가 손상신호를 외부로 발신하게 된다. 이러한 기능성 건축부재에 대한 연구는 이상 기후 현상과 지진 등으로부터 건축물이나 주요구조물을 보호하는데 중요한 역할을 담당할 것으로 사료된다.

Currently, graphene is a topic of very active research in fields from science to potential applications. For various radio-frequency (RF) circuit applications including low-noise amplifiers, the unique ambipolar nature of graphene field-effect transistors can be utilized for high-performance frequency multipliers, mixers and high-speed radiometers. Potential integration of graphene on Silicon substrates with complementary metal-oxide-semiconductor compatibility would also benefit future RF systems. The future success of the RF circuit applications depends on vertical and lateral scaling of graphene metal-oxide-semiconductor field-effect transistors to minimize parasitics and improve gate modulation efficiency in the channel. In this paper, we highlight recent progress in graphene materials, devices, and circuits for RF applications. For passive RF applications, we show its transparent electromagnetic shielding in Ku-band and transparent antenna, where its success depends on quality of materials. We also attempt to discuss future applications and challenges of graphene.